Piezoelectricity is the ability of certain materials (e.g., crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) to convert mechanical energy into electrical energy or vice versa. Piezoelectric materials can be useful in numerous areas of application such as generating high voltage and/or power sources, sensors, or actuators, etc.
Conventional piezoelectric materials such as certain ceramics or synthetic polymers such as polyvinylidene fluoride may not be suitable for biomedical and biotechnological application due to lack of biocompatibility and biodegradability.
Silk fibroins of natural silkworm fibers have shown some shear piezoelectricity. See Ando et al., Reports on Progress in Polymer Physics in Japan 23, 775-8 (1980); Fukada, J. Phys. Soc. Jpn. 11, 1301 (1956); Harvey, Science 89, 460-1 (1939). Early research suggests that a reddish luminescence formed by shaking of silk fragments may be attributed to their piezoelectricity. See Harvey, Science 89, 460-1 (1939). However, this study was to focus on the natural silk fiber, rather than the regenerated silk matrix. Moreover, there has not been any insight into the mechanisms and structural changes that may be associated with the phenomena observed with silk materials. More importantly, no further studies have been provided to control silk piezoelectricity at a desired level for various applications. Hence there is still a need in the art to develop a piezoelectric material that can be biocompatible and controllably biodegradable for applications such as biomedical materials, tissue engineering and medical devices.